Chronic cutaneous ulcers are lesions on the skin that result from the body's inability to heal. The causes of chronic ulcers range from decreased blood flow to tissues stemming from persistent pressure, to systemic changes in metabolism that result from underlying pathologies such as diabetes. The inability of cells to deposit fibronectin (FN) into the extracellular matrix (ECM) is thought to contribute to the pathogenesis of chronic ulcers. The goal of this project is to promote chronic wound healing by providing cells in the wound with a synthetic ECM form of FN. FN is incorporated into the ECM via a tightly regulated cell-mediated process. ECM FN specifically increases cell proliferation, cytoskeletal organization, and ECM deposition. A cryptic heparin-binding site in FN's first type III module (FNIII-1H) mediates ECM FN cellular effects. Incorporation of FN into the ECM and exposure of FNIII-1H require exertion of cell-and/or tissue-derived forces on the molecule. Ultrasound is a form of mechanical energy that can propagate deep into tissues. US interacts with bulk tissues and macromolecular structures such as cells and proteins. US can interact with, and disrupt, protein quaternary structures. I hypothesize that mechanical forces associated with US can be used to 'activate'FN by inducing conformational changes that result in multimerization or the exposure of FNIII-1 H, and that addition of US-activated FN can promote chronic wound healing. My data show that ECM-FN specifically increases cell proliferation in an in vitro model of impaired wound healing. My data also suggest that US can induce FN multimerization. These data suggest that an US- activated ECM form of FN could promote chronic wound healing by bypassing the need for cell-dependent activation of FN. The aims of this proposal are: (1) Determine the effects of FN on the proliferation of myofibroblasts in an in vitro model of impaired wound healing;(2) Characterize the acoustic parameters that 'activate'FN by inducing multimerization or exposing FNIII-1 H;(3) Determine the effects of US-activated FN on the proliferation of myofibroblasts in an in vitro model of impaired wound healing;and (4) Determine the effects of US-activated FN on the rate of wound closure in a mouse model of impaired wound healing. PUBLIC HEALTH RELEVANCE: Chronic cutaneous ulcers affect approximately 7 million people per year. Current therapies have had limited success in promoting chronic wound healing. The goal of this project is to promote chronic wound healing by providing cells in the wound with a synthetic ECM form of FN.